1. Field of the Invention
The present invention relates to an acoustic output processing apparatus for processing an acoustic output to be produced clearly by automatically selecting and correcting with emphasis a most important sound for a user from among various sounds produced within a room, such as the output of car audio, an acoustic guide for a car navigation system, and an acoustic output of a hands-free telephone. The invention also is capable of processing an acoustic output, including other acoustic output processing, corresponding to a priority order of various delivered sounds.
2. Description of the Related Art
Recently, acoustic guides are produced by various devices, and acoustic outputs are produced by various devices such as an audio system and TV. In vehicles in particular, acoustic guides are often provided by car navigation systems. Moreover, as mobile phones are becoming widespread, drivers frequently take them into vehicles so as to receive calls. Also, hands-free telephone devices are used for safer driving. In this case, sounds heard on the other end may be produced by an audio system in the vehicle other than an earphone and a speaker disposed close to a user.
Such an acoustic guide for a car navigation system is for guiding a driver to drive along a guidance route. It vocally performs guidance sequentially in various modes, especially for turning right or left at a crossing ahead while displaying route images on a screen. In order to enable a driver to follow a guidance route without needing to view the images, the acoustic guide is particularly important in the function of the navigation system.
Such an acoustic guide is produced while various kinds of noise enter a vehicle cabin and vary according to the vehicle travel state, such as an engine sound, wind noise, and a tire friction sound. There may sometimes be speaking voices of vehicle occupants, various kinds of music from an audio system, and radio news announcements while the acoustic guide is produced.
Furthermore, a TV monitor may sometimes be provided in a rear seat area and viewed by a vehicle owner or a family member. Therefore, within a cabin of a moving vehicle, with TV sound or telephone voices from a user or the other end of the hands-free phone, the acoustic guide of the navigation system may be produced.
In order to certainly convey the navigation acoustic guide to a user under such various kinds of noise and voices, it is preferable not to increase the power of the acoustic guide output needlessly, but it is preferable to adjust the sound volume corresponding to the state of the noise. In order to solve this problem, Japanese Unexamined Patent Application Publication No.11-166835, assigned to the same assignee as this application, discloses a navigation acoustic output correction device. In this device, on the basis of a sound pressure level of the navigation acoustic guide and a sound pressure level of ambient noise audible at a listening position, gain correction of the acoustic guide is performed.
According to the Publication mentioned above, noise components captured by a microphone disposed in the cabin are separated from the acoustic guide so as to obtain a sound pressure for each frequency band in advance, and the sound pressure gain for each frequency band of the navigation acoustic guide is obtained corresponding to the sound pressure of each noise, so that the sound pressure gain of the navigation acoustic guide is established based on this gain, enabling an appropriate sound pressure of the acoustic guide corresponding to the ambient noise to be obtained.
As described above, in a vehicle cabin, various acoustic output devices are used, and an acoustic guide is performed as needed as an important function of a car navigation system. By means of the technique described above, the acoustic guide can be performed with an appropriate sound pressure corresponding to acoustic outputs from surrounding devices or ambient noise; however, the target acoustic output to be clearly produced is only the navigation acoustic output, and the target acoustic output is separated from the other sounds in advance from among various sounds captured by the microphone disposed in the cabin.
The navigation acoustic output correction device described above is only effective for the navigation sounds established in advance. In order to clearly hear the voice of a hands-free device, for example, a circuit for separating the sound of the hands-free device from the other sounds and adjusting means for adjusting the sound gain of the hands-free device would need to be provided. With the other devices, similar means must be provided for clearly hearing them.
Providing a similar processing circuit for each device in such a manner wastefully complicates the configuration. Therefore, it is assumed the circuit is provided for a device desired by a user; however, there may be a large variety of user preferences, so that all of the preferences cannot be satisfied. Therefore, these demands cannot be satisfied by the technique described above.
Also, while the acoustic output of the hands-free device is being corrected with priority, when the guidance at an intersection to turn right or left is produced from the navigation system, the hands-free device assumes the acoustic guide output to be noise so as to produce its own output with a sound pressure larger than that of the acoustic guide output, so that the navigation acoustic guide cannot be heard and a driver may miss the guidance path.
Conversely, if the navigation acoustic guide is selected as the priority, and a comparatively unimportant guide such as the description of adjacent facilities is produced, if an important call is received by the hands-free device, the navigation system assumes the hands-free output to be noise so as to produce its own output clearly with a sound pressure to cancel the hands-fee output, so that the phone voice is scarcely heard.
As described above, there are a large variety of acoustic output devices in a vehicle cabin, such as an audio system, a hands-free device of a mobile phone, and a TV, each having a specific mode of operation. That is, in the audio system, a piece of favorite music may be heard as background music while canceling ambient noise so that it may be unimportant for users. The sound on the other end of the mobile phone produced by a speaker of the hands-free device may be frequently heard with concentrated attention as comparatively important voice for a user. Also, the TV sound is continuously produced so as to be unimportant; however there may be comparatively important information such as a news program.
Moreover, in the acoustic output of the navigation system, although it is especially important to guide a driver to turn right or left at an intersection as mentioned above, there are cases, in which the guidance for going straight is not so important; the description of facilities performed by the demand of a user does not create a problem even when being somewhat delayed; the guidance performed upon arrival at a destination is rather important so as to prevent a driver from going past; and the guidance informing a driver of congestion along the guidance path direction by a VICS (vehicle information and communication system) is comparatively important. Nevertheless, there are occasions when it is undesirable to give the navigation acoustic guide correction priority.
Even when there are provided a voice processing circuit for clearly listening to the navigation acoustic guide, a voice processing circuit for clearly listening to the acoustic output of a hands-free device, and further a voice processing circuit for clearly listening to a TV, when these acoustic outputs are overlapped, each correction is performed by increasing the source's sound pressure assuming the other sounds to be noise, resulting in an extremely undesirable situation.
As a countermeasure for the problems mentioned above, the acoustic output important for a user is designated in advance and the correction for clarifying this acoustic output is performed only when this acoustic output is to be produced. However, in this case, although it is responsive to various acoustic outputs, only the device selected by a user in advance performs emphasis correction for clarifying it, and other acoustic outputs cannot be corrected with emphasis.
Furthermore, as another countermeasure, while the audio system is being heard, noise outside is processed for elimination; a user selects to correct the navigation acoustic guide upon starting of important guidance; or the acoustic output of a hands-free device is switched to be clear upon receiving a mobile phone call, so that the acoustic output deemed most important is to be switched as needed on the audio device side. However, in this case, a user must select the device deemed most important, so that this operation is bothersome and undesirable especially for a driver for safety sake.
The above problem arises not only in a vehicle cabin but also in the home where an audio system and various acoustic guides of devices surrounding the audio system are widely used recently.